Azo dyestuffs



Patented May 19, 1942 AZO DYESTUFFS Friedrich Felix, Basel, andRudolf von Capeller, Rliehen, Switzerland, assignors to the firm Society of Chemical Industry in Basle, Basel, Switzerland No Drawing. Application November 7, 1940, Se-

rial No. 364,750. In Switzerland September 18,

6 Claims. (Cl. 260205) This application is a continuation-in-part of our application Serial No. 239,404 of November 7, 1938, which is itself a division of our application Serial No. 218,221 of July 8, 1938. 'In the first named application there are described, among other things, azo-clyestufis of the general v z p formula in which R1, R2 and :6 have the meanings ala1ky1ene O C COOH ready given, in an organic solvent, for example, II toluene, wlth oxahc acid in such a manner that 10 at least one molecule oxalic acid is used per 1 molecule of dyestuff; In this way, esterification takes place, with formation of water. In order m Whlcl} R1 F epresent nuclel of the to prevent the water formed from stopping the Zelle Serles, 1n Whlch the group reaction, care is taken that the water formed a1ky1ene O C y COOH is removed continuously by partial distillation II of the solvent. The dyestuffs which serve as parent substances in the present process are thus obtained by al- L lowing diazo compounds of amines-of the general stands 1n th para-P05111011 to the am-group and formula NO2RNH2, in which R stands for in which x represents hydrogen or, alkyl, this .term including also substituted alkyls, such as an by treating an azo-dyestufi of the general formula alkylene O H a benzene nucleus and in which the N02 'and NH2 groups are in the para-position to one another, to act in known manner on amines which are free from sulfo and carboxyl groups 0 and which are of the general formula and in which the z z I I l alkylene-OH and the COOH groups are united by the connecting link y.

In this application it is further stated that v in which a: has the meaning-already given and in which .2 represents hydrogen or a substituent which does not opposethe coupling of the amine with diazo compounds in the para-position to the alkylene-OH group Some of the dyestuffs obtainable by the present process are, for example,

Dyes acetate rayon- 1 3 Red orange.

/CH2CH2.O.CC O OH I I C2115 2 u Ruby red.

' /OHzCH .O.C-COOH NO N.= ON

. 03H}; Cl

byes acetate Trayon- Y -O Blue.

01 con.

- CHI-CHr-CH1OCC O OH NO: N=N N\ v V on on o-c-ooon N NHC'Of-CH:

h g 1 0 Brown.

/CH:CHr-OOGOOH NO: N= ON\ OH:CHr-0COOOH 1 CH: ll 0 These dyestufis, which, in the free state, 'corin which 2 stands for hydrogen or a substituent respond to the general formula which will not oppose the coupling with diazo z compounds in the 4-position to the N0 RiN=NRa-N 8lky1Bn8-0(%COOH in which R1 represents a nucleus of the benzene and rePresents a hydrogen an alkyl Series in which the N02 and the group (thls term includes alsosubshtuted alkyls are in the para-position to one another, in which, such a CH 2 CH2 OH grqup)' R2 also represents a nucleus of the benzene series g gf gsf 33 t 2112522 5253 333x 32 I 0 r0 m whlch the N N g ups and the taken that the water liberated be removed from f the reaction medium at themoment of its forma- N 7 group tion by partial distillation ofthe solvent. In

\amy1ene o C CO0H this manner, bases of the general formula 7 7 35 I z z 7 ll t are in the para-position to'one another, and in I F Q which :1: stands for a member selected from the group consisting of hydrogen and an alkyl radical, alkyl including also substituted alkyl, are re- 40 z 7 z' r markable for their excellent dyeing properties. Obtained, in which and have the mean. They form Orange to met-brown W ings already given, which possess the surprising ye u as h above table Shows Whlch 1n property of being stable to water. It is actually t e r of thelr free afflds and also in the known that the acid alkyl esters, of oxalic acid of their Salts, @Y Partlculafly acetate rayon m areimmediately-saponified bywater (cf. Berichte thecorrespondme shadesaccount their der deutschen Chemischen Gesellschaft, vol. 16, ready solubility in water then use is especially page 2413 simple. V 7 Thanks to their surprising stability, these in- O partwular a e e those r es ufisw termediate products, by combination with diazo conta-m the atomic grouping V compounds of the benzene series, preferably those which are free fl0m SO3H and COOH g groups and which contam an N02 group in the I para-position to the d azo group, may be built 7 up into the same 'dyestufis which, as already de- CH|OH,0-0-GO0H scribed, maybe obtained by esterification of the l finished dyestuff.- v The following examples describe the present or F dyestllfis W consist of mlxtms m invention without in any way restricting it, the which, in addition to dyestuffs with the above parts being by weight atomic grouping, are dyestufis which possess the I atomic grouping le 1 V o 10 parts of they dyestuff obtained by diazotiza- CH -GH -OC--COOH tion of l-aminol-nitrobenz ene and coupling with 1 molecule of N-(ethyl-B-hydroxyethyl) r am nobenzene are mixed with 3 10 parts of an- Q Q hydrous oxalic acid, and 300 parts of toluene are Another method of preparing these dyestufis added to the mixture, which is then heated to consists of treating-withoxalic acid, in the presthe boiling point for 3 hours, the water formed ence of an organic solvent, amines of the general by the esterification beingy a ble fgrmula, I I apparatus whilst the toluene which also distils Z 2 is condensed and returned to the reaction vessel. When the reaction is; completed, the toluene is N removed by distillation, the solid residue is broken up, the excess of oxalic acid which. may a z be present is extracted with water and the reaction product is then neutralized with ammonia in the presence of water. The aqueous solution or suspension of the dyestufi thus obtained is either distilled in vacuo or the dyestufi is precipitated by means of sodium chloride, filtered at the pump and dried in vacuo. formed is a dark powder which is readily sol- The dyestuff uble in water and which dyes acetate rayon in red-orange shades.

Example 2 A solution of 165 parts of N-(ethyl-B-hydroxyethyD-aminobenzene and 135-180 parts of:

anhydrous oxalic acid in 1500 parts by volume of toluene is heated for 3 hours to the boiling point, the water formed during the esterification' being trapped and removed from the reaction mixture. When the reaction is complete the toluene is removed by distillation and the remaining transparent residue which is viscous when warm but solid when cold; is dissolved in five to ten times its quantity of warm water. The clear solution reacts acid and may be used in this form for the manufacture of the dyestuff.

Example 3 The aqueous solution of the acid oxalic'ester. of Example 2 is added to the ice-cold diazo solution prepared by diazotizing 138 parts of l-amin-4-nitrobenzene with 69 parts of sodium nitrite in hydrochloric acid solution by known methods. The coupling is brought to a conclu sion by addition of sodium acetate solution,the dyestufi being thus precipitated to a great extent. The dyestufi suspension is then neutralized with aasasav;

Example 6 0.5 part of the dyestuff obtained in Example 1 is dissolved in 3000 parts of water. 40 parts of sodium sulfate crystals are added to this dyebath and 100 parts of acetate rayon yarn are worked in the bath for 1- hour at 80 C. After rinsing and drying, the acetate rayon is found to be dyed in a pure red-orange. shade.

1. The unsulfonated azo-dyestuffs which, in

the free state, correspond to the general formula in which R1 represents a nucleus of the benzene series, in which the' N02 and the-N N-- groups are in the para-position t o one: another in which R2 also represents a nucleus of the benzene series ammonia and the dyestufi itself is completely precipitated by addition of sodium chloride, after which it'is filtered at the pump, washed with cold water and dried in vacuo. The dyestufi is readily soluble in hot water and dyes acetate rayon like the dyestufi described in Example 1.

If l-aminoi-nitrobenzene be replaced by 1- amino-2-chloro-4-nitrobenzene, a similar, watersoluble dyestufi is obtainedv which dyes acetate rayon in ruby red shades. With 1-amino-2- methoxyl-nitrobenzene a product is obtained which dyes acetate rayon in red shades from it's aqueous solution.

Example 4 A solution of 195 parts of N-B-dihydrox'ydiethyl-3-methyl-aminobenzene and 270 parts of anhydrous oxalic acid in 2800 parts by volume of toluene is heated to the boiling point for 2 hours, the water formed during the esterification being trapped and removed from the reaction mixture.

When the toluene has been distilled away, a

transparent, viscous mass remains, which forms a clear solution after neutralization of the aqueous mixture with ammonia. The solution thus obtained may be used directly to couple with suit-' able diazo components.

I Example 5 If,-to,the solution of the acid oxalic acid ester of N-p-dihydroxydiethyl -3-methylaminobenzene obtained in Example 4, the: diazo solution, ob-

tained by diazotization-of 138 parts of l-aminoe 4-nitrobenzene by known methods,- be added, and

, the coupling be brought to a conclusion by addition of sodium acetate until the mineral acid reaction disappears, a dyestufi is obtained by working up the i'esulting product in the manner described in Example 3 which is directly soluble in cold water and which dyes acetate rayon fast red shades. A 1

in which the -N=N- group and the N i group f a1k 1e o-o-c 0 on are'in the para-position to, one another, and in which a: stands for a member-- selected from the group consisting-,ofhydrogen, an alkyl radical,

radical, which products, in the form of their alkali salts, form water-soluble powders which dissolve inwater to solutions which are orange to ed, brow h etrb e n -i, e

.. 2. {I'he; -unsulfonated azo-dyestuffs which, in

the free state, correspondto thegeneral formula =:L .l iii-which Elf-represents a'nucleus ofthe benzene series-in which the N02 and the -'N=N groups are in the para-position to one another, in-which' R2 also represents a' nucleus'of the benzene series in which the -N=N"' group and the are in the para-position to one another, and inwhicharstands for amember selected from the group consisting of hydrogen, an"alkyl radical,

" alkylne-O-(F-COOH in which R1 represents a nucleus of the benzene CHrCHz-O-C-C O OH I NO N=NON\ I) CHrCHr-O-C-C O OH N CH: I0] I NO:- N=NO-N 5. The dyestufi which corresponds in the free state to the formula 6. The dyestuff which corresponds in the free state to the formula Y .01 I I CHa-CHz-O- FRIEDRICH RIUDOLF VON CAPELLER; 

